Substituted 2-arylbenzazole compounds and their use as antitumour agents

ABSTRACT

Substituted 2-phenylbenzazole compounds of formula (I) wherein X represents S or O and Q represents a direct bond, —CH2— or —CH═Ch—, exhibt selective antiproliferactive activity in respect of mammalian tumour cells. At least in preferred enbodiments the benzene ring of the benzazole nucleus has a halogen substituent, preferably flourine, and the 2-phenyl group has a 4′-amino substituent which may be conjugated with an amino acid to provide a water soluble amino acid amide prodrug or salt thereof.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a national phase application based onPCT/GB00/03210, filed Aug. 21, 2000. These application in its entiretyis incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to 2-arylbenzazole compounds. It isarticularly concerned with such 2-arylbenzazole compounds which arebiologically active, especially in respect of an ability selectively toinhibit proliferatiory of certain mammalian tumor cells. The inventionis also concerned with compositions containing such 2-arylbenzazolecompounds for use in therapy, especially antitumour therapy, and withthe preparation thereof. In addition, the invention provides2-arylbenzazole compounds which represent useful new chemical entities.

BACKGROUND AND SUMMARY OF THE INVENTION

Various 2-arylbenzazole compounds found to be active in inhibitingproliferation of certain tumor cells and exemplified by2-(4′-aminophenyl)benzothiazole and close analogues or acid additionsalts thereof are disclosed in PCT international patent publications WO95/06469 and WO 96/26932.

For some of the benzazole compounds disclosed in WO 95/06469, forinstance the compound 2-(4′-aminophenyl)benzothiazole which has beendesignated the reference code CJM 126, a remarkably high specificinhibitory activity has been found in respect of certain human breastcancer cell lines. In WO 96/26932 compounds such as2-(4′-amino-3′-methylphenyl)benzothiazole (reference code DF203) forexample have been disclosed that exhibit anti-proliferative activityselectively in respect of a number of different cell lines that relateto a range of various mammalian cancers other than human breast cancer.

It has now been found that by modifing the structure of the prior artcompounds their antitumour activity may be improved, whilst retainingthe selectivity.

As indicated, the compounds with which the present invention isconcerned include 2-arylbenzazole compounds that are of particularinterest as active chemotherapeutic agents for use in therapy,especially antitumor therapy, by virtue of arn ability to inhibitproliferation of certain tumor cells. Moreover, at least some of thecompounds concerned are believed to be novel or new chemical entities.Furthermore, methods are provided for preparation or synthesis of thecompounds, as hereinafter described. Also, in some cases the compoundsare of interest as intermediates useful for the preparation of other2-arylbenzazole compounds for use as active chemotherapeutic agents.

More particularly, according to a first aspect of the invention there isprovided a compound of formula

wherein

-   -   X represents S or O;    -   R¹ is selected from fluoro, iodo and trimethyltin;    -   R² represents hydrogen, NO₂, N₃, halogen, alkyl, a halo        substituted or hydroxy substituted akli, CN or CF₃;    -   R³ represents hydrogen, halogen, alkyl, or a halo substituted or        hydroxy substituted alkyl;    -   R⁴ represents alkyl, a halo substituted or hydroxy substituted        alkyl, hydroxyl, alkoxy or aralkoxy;    -   R⁵ and R⁶ each independently represent hydrogen, an amino acid,        an alkyl, or a group        wherein Y represents O or S, and R⁷ represents alkyl or        —CH(R⁸)NH₂ where R⁸ represents hydrogen or an optionally        substituted alkyl such as a hydroxyalkyl or amino alkyl for        example;    -   Q represents a direct bond, —CH₂— or —CH═CH—;    -   p represents zero, 1 or 2; and    -   n represents zero, 1, 2 or 3;    -   or a prodrug and/or a pharmaceutically acceptable salt thereof;        subject to the following provisos:    -   (a) alkyl or substituted alkyl groups are linear, branched or        cyclic structures but when present as linear or branched        structures in the compound or as a moiety in another group such        as alkoxy they are composed of less then ten carbon atoms, and        preferably of less than 6 carbon atoms.    -   (b) p represents zero or 1 when n represents 3;    -   (c) when n represents zero, R⁵ or R⁶ represents —C(Y)—CH(R⁸)NH₂;    -   (d) where a group is optionally substituted, unless otherwise        specified the or each substituent is selected from halogen, OH,        SH, NH₂, COOH and CONH₂;

In this specification the following definitions apply in respect ofcertain terms used herein:

-   -   “Aryl” dienotes a carbocyclic group or structure having at least        one aromatic ring (e.g. phenyl) that in some cases may form part        of a multiple condensed ring structure;    -   “Aralkyi” denotes a lower alkyl group, i.e. a cyclic, branched        or straight chain alkyl group of one to six carbon atoms, in        which there is an aryl substituent;    -   “Optionally substituted aryl” or “optionally substituted        aralkyr” denotes aryl or aralkyl groups optionally substituted        with one or more functional groups; and    -   “halo” denotes a fluorine, chlorine, bromine or iodine atom.

Also, the term prodrug is used in the present specification to denotemodified forms or derivatives of a pharmacologically active compoundwhich biodegrade in vivo and become converted into said active compoundafter administration, especially oral or intravenous administration, inthe course of therapeutic treatment of a manunal. Such prodrugs arecommonly chosen because of an enhanced solubility in aqueous media whichhelps to overcome formulation problems, and also in some case to give arelatively slow or controlled release of the active agent.

According to a second aspect the invention provides 2-arylbenzazolecompounds as defined above for use in therapy. In this case, however,when n represents 1, 2 or 3, R¹ will usually be fluorine or iodine. Theinvention also provides pharmaceutical compositions comprising orcontaining such compounds in a form ready for administration to a mammalin need of treatment therewith.

In preferred embodiments R¹ will commonly represent F, preferably butnot necessanfly in the 5-position. n preferably represents 1 or 2. Also,when one of R⁵ and R⁶ represents —C(Y)—CH(R⁸)NH₂, the other preferablyrepresents hydrogen.

Fluorine substituted compounds of the invention may incorporate theisotope ¹⁸F. Such ¹⁸F-substituted compounds provide a further aspect ofthe invention and are of use for imaging purposes, for example aspositron emitting tracers for use in positron emission tomography (PET).By administering a small amount of such ¹⁸F-substituted compoundsfollowed by carrying out positron emission tomography in accordance withknown techniques, preliminary tests may be carried out to assess theeffectiveness of such compounds against a particular tumour in a patientunder investigation, or to diagnose the presence of a suspected tumourusing an ¹⁸F containing compound of known antitumour efficacy.

One particular ¹⁸F labelled compound useful as a tracer for positronemission tomography in tumour diagnostic studies is 5- or 6¹⁸Fluoro-2-(4′-amino-3′-methylphenyl)benzothiazole and amino acidconjugated prodrug forms and/or salts thereof. This may be convenientlyprepared from the corresponding 5- or 6-iodo substituted compound ashereinafter described.

Preferred compounds of formula (I) wherein p represents 1 includecompounds in which R⁴ represents alkyl, alkoxy or benzyloxy. Alkyl,however, may be substituted by halogen or by hydroxy. It is also usuallypreferred that X represents sulphur.

Preferred compounds of formula (I) may also be further characterised byat least one of the following features:

-   -   (a) at least some alkyl groups when present as such or as a        moiety in other groups such as alkoxy are methyl or ethyl;    -   (b) where a substituent represents or incorporates halogen, such        halogen is selected from fluorine, iodine, bromine and chlorine.

A suitable prodrug of a compound of formula (I) is an amino acid amidewhich may be formed by conjugating the compound with the amino acid inquestion, e.g. alanine, lysine or sermne. Thus R⁵ or R⁶ optionallyrepresents —C(O)—CH(R⁸)NH₂ or a salt thereof. Examples of suitablesubstituents for R⁸ to represent include hydrogen, —CH₃, —(CH₂)₄NH₂ or—CH₂OH. The stereochemistry of the R⁵ or R⁶ substituent is either D or Lor it is a racemic mixture. The L-stereoisomer is generally preferred.

It has been found that at least for compounds of formula (I) wherein R⁵and R⁶ both represent hydrogen, i.e. wherein the phenyl group has a4′-NH₂ substituent, a very effective degree of anti-proliferativeactivity against various mammalian tumor cells may arise when R²represents a halogen atom, or represents a C₁-C₅ lower alkyl group(preferably Me or Et), in the 3′position of the phenyl group. Forexample, the particular combinations of 4′-NH₂ and 3′-F, 4′-NH₂ and3′-Cl, 4′-NH₂ and 3′-Br, 4′-NH₂ and 3′-I, 4′-NH₂ and 3′-Me, and 4′-NH₂and 3′-Et in the phenyl group of the 2-aryl component have been found toyield compounds with potent anti-proliferative properties against atleast some selected tumor cells. The 3′ position substituent mayalternatively be substituted by a cyano group, giving a furthercombination 4′-NH₂ and 3′-CN.

Compounds of formula (I) wherein R² is a 3′-substitueni in the phenylgroup, and which are of particular interest, include those compoundswhere p represents zero, R⁵ and R⁶ both represent hydrogen, and thecombination of substituents R³, X and R² is selected from one of thefollowing combinations:

R³ X R² H S 3′-Me H S 3′-Et H O 3′-I H S 3′-Br H S 3′-Cl H S 3′-CN 5′-BrS 3′-Br 5′-Cl S 3′-Cl 5′-Me S 3′-Cl H S 3′-F

Another series of benzazole compounds which provide some very promisinganti-proliferative agents for use in antitumor therapy are compounds offormula (I) wherein R¹ is fluorine or iodine and the substituent NR⁵R⁶is a group

wherein, as hereinbefore specified, Y represents O or S and R⁷represents the group —CH(R⁸)NH₂ where R⁸ is as previously defined.

Particular preferred compounds of formula (I) are those wherein prepresents zero, X represents S, wherein R³, R⁵ and R⁶ each represent H,wherein Q represents a direct bond, and wherein n, R¹ and R² representone of the following combinations:

Compound n R¹ R² of formula 1 4-F 3-CH₃ (Ia) 1 6-F 3-CH₃ (Ib) 1 4-F H(Ic) 1 6-F H (Id) 2 4,5-diF 3-CH₃ (Ie) 2 4,6-diF 3-CH₃ (If) 2 5,7-diF3-CH₃ (Ig) 1 7-F 3-CH₃ (Ih) 2 5,6-diF 3-CH₃ (Ii) 2 6,7-diF 3-CH₃ (Ij) 15-F 3-CH₃ (Ik) 1 5-F H (Il) 1 4-F 3-I (Im) 1 5-F 3-I (In) 1 6-F 3-I (Io)1 4-F 3-Cl (Ip) 1 5-F 3-Cl (Iq) I 6-F 3-Cl (Ir) 1 4-F 3-Br (Is) 1 5-F3-Br (It) 1 6-F 3-Br (Iu)

A further particularly preferred compound is a compound of formula (I)wherein p represents zero, X represents S, Q represents a direct bond,one of R⁵ and R⁶ represents H and the other represents —C(Y)R⁷ wherein Yrepresents O and R⁷ represents —CH(R⁸)NH₂, and wherein R³ represents H,and n, R¹, R² and R⁸ represents one of the following combinations:

Compound n R¹ R² R⁸ of formula Zero — H —CH₃ (Iv) Zero — 3-CH₃ —CH₃ (Iw)Zero — 3-Cl —CH₃ (Ix) Zero — H —(CH₂)₄NH₂ (Iy) Zero — 3-CH₃ —(CH₂)₄NH₂(Iz) Zero — 3-Cl —(CH₂)₄NH₂ (Iaa) Zero — 3-CH₃ —CH₂OH (Iab) 1 6-F 3-CH₃—CH₃ (Iac) 1 5-F 3-CH₃ —(CH₂)₄NH₂ (Iad) 1 6-F 3-CH₃ —(CH₂)₄NH₂ (Iae) 15-F 3-CH₃ —CH₃ (Iaf) 1 5-F 3-CH₃ H (Iai)

It will also be understood that many of the compounds in accordance withthe invention may be in the form of pharmaceutically acceptable salts,especially acid addition salts derived from an acid selected for examplefrom the group comprising: hydrochloric, hydrobromic, sulphuric, nitric,phosphoric, maleic, salicylic, ptoluenesulphonic, tartaric, citric,lactobionic, formic, malonic, pantothenic, succinic,naphthalene-2-sulphonic, benzene-sulphonic, methanesulphonic andethanesulphonic.

It should also be understood, however, that where reference is made inthis specification to compounds of formula (I) such reference should beconstrued as extending not only to their pharmaceutically acceptablesalts but also to other pharmaceutically acceptable bioprecursors(prodrug forms), especially amilo acid amide derivatives as hereinbeforereferred to, where relevant Moreover, where any of the compoundsreferred to can exist in more than one enantiomeric form or containatoms which have more than one isotope, all such enantiomeric forms orisotopic compounds, mixtures thereof, and their preparation and uses arewithin the scope of the invention.

The invention also comprises the use of a 2-arylbenzazole compound ashereinbefore specified for making a medicament or pharmaceuticalcomposition, especially for selective use in antitumor therapy.

As hereinafter more particularly described, pharmaceutical compositionsor preparations in accordance with the invention for selective use inantitumor therapy will generally contain or provide a therapeuticallyeffecfive antitumour amount of the active compound, and will beformulated in accordance with any of the methods well known in the artof pharmacy for administration in any convenient manner, and may forexample be presented in unit dosage form admixed with at least one otheringredient providing a compatible pharmaceutically acceptable additive,carrier, diluent or pharmaceutically inert excipient.

Biological Results

In vitro Cytotoxicities

In carrying out the following cytoloxicity assays, the method usedcorresponds substantially to the following example:

-   -   Cells were maintained in a continuous logarithmic culture in        RMPI 1640 with L-glutamine medium, supplemented with 10% fetal        calf serum, penicillin (100 IU/ml) and streptomycin (100 μg/ml).        The cells were mildly trypsinized for passage and for use in        assays.    -   On day one, 180 μl of trypsinized tumour cells (5×10³ ml⁻¹) were        placed in the wells of 96-well, flat-bottom microtiter plates.        Columns 1 and 12 were filled with 300 μl medium to protect from        evaporation. The plates were incubated for 24 hours at 37° C.        and 5% CO₂ in air to allow the cells to adhere and resume        exponential growth prior to the addition of drugs. The compounds        being tested were dissolved in DMSO and stored as 10 mM stock        solutions at 4° C., protected from light. Serial dilutions at a        10× concentration were prepared in growth medium so that the        final concentration of DMSO exposed to cells did not exceed 1%.    -   On day two, 20μl of growth medium was added, to the wells of        column 2 to act as a control. 20 μl of drug dilution was added        to the other wells with the lowest concentration in column 3 and        the highest concentration in column 11. The plates were        incubated for 72 hours at 37° C. and 5% CO₂ in air. Each        compound was tested in triplicate. At the time of drug addition,        a plate of untreated cells was read to provide an initial        optical density value for use in the calculation of the IC₅₀.    -   On day five the plates were read. 50 μl MTT (1 mg/ml⁻¹) was        added per well and the plates incubated for a further 4 hours.        The MTT is metaboliscd to form a blue formazan product. The MTT        solution was aspirattd and 125 μl DMSO:glycine buffer (4:1) was        added. The plates were placed on a plate shaker until the        fornazan crystals had dissolved and absorbance was ready at 550        nm on a plate reader.    -   For each compound tested, a dose response curve was obtained and        the IC₅₀ statue (drug concentration at 50% inhibition of cell        growth) was calculated.

It has surprisingly been found that many of the compounds of formula (I)are highly potent, inhibiting 50% cell growth at <10 nM. Examples of theresults of in vitro cyctotoxicity tests carried out using MCF-7 andMDA468 cell lines are presented at the end of this description in TABLE1 which shows IC₅₀ values as determined by 3-day MTT assays. (n=8) for arange of compounds in relation to MCF-7 and MDA 468 cell lines.

The selectivity of antitumor effect of the fluorinated compounds of theinvention has been found to be very similar to that found for the priorart compounds disclosed in WO 96/26932, with antiproliferative activityobserved in the same cell lines that were growth inhibited by theirrespective non-fluorinated parent compounds, e.g., breast MCF-7 and MDA468 cells. Prostate PC 3 and non-malignant breast HBL 100 cells wereunresponsive to compounds of the invention.

One feature of the prior art compounds is that they show a biphasicdose-response relationship specifically in sensitive cell lines: cellkill occurs at low nanomolar concentrations of the compounds, followedby a potentially undesirable proliferative response at low micromolarconcentrations (termed the “second growth phase”). However, it hassurprisingly been found that the biphasic response is eliminated in somecompounds of the invention, especially when R¹ represents 5-F or 7-F asin compounds Ik and Ib.

In addition to breast (MCF-7, TA47D), ovarian (IGROV 1, OVCAR 3), andrenal (TK 10) cell lines, the compounds of the invention wherein R¹ isfor example 5-F have been found to be active against colon (HCC 2998)cell lines in a standard 2 day sulforhodamine B assay—in contrast, thesecolon cell lines respond to the non-fluorinated prior art compounds onlyafter prolonged 6 day exposures.

Among the prodrugs, 2-(4′-amino-3′-methylphenyl)-5-fluoro-benzothiazolealanine (alanyl amide hydrochloride salt—compound Iaf) shows outstandingantitumour potency, with IC₅₀ in MCF-7 cells>5 fold lower than that ofother anido prodrugs. None of these prodrugs elicits the biphasicdose-response.

NCI mean graphs of the amino acid salts are similar to those of theirrespective parent compound, with selective antitumour activity againstcertain ovarian (OVCAR-5), renal (TK-10) and breast (MCF-7, T-47D) celllines.

In vivo Xenogaft Studies

The compounds of formula (Ib) and (Ik) were evaluated for in vivoantitumor property in ER positive MCF-7 and ER negative MT-1 humanbreast tumor xenografts implanted in nude mice using the experimentaldetails described at pages 11 and 12 of WO 96/26932. Significant growthinhibition of MCF-7 xenografts was observed with both compounds giveni.p., with the 5-F compound of formula (Ik) being toxic at 12.5 mg/kg.In the MT-1 xenografts, the compound of formula (Ik) was toxic at 25mg/kg; at the lower dose of 12.5 mg/kg, the (6-F) compound of formula(Ib) produced more pronounced growth inhibition than did the same doseof the compound of formula (Ik) although both analogues causeddose-dependent tumor growth inhibition and weight loss. Blood parameters(white blood cell and platelet counts) and the level of livertransaiminases were not adversely affected by either compound.

The in vitro growth inhibitory property of the compounds of formula (Iw)and (Iz) is paralleled by significant in vivo growth retardation ofhuman breast tumour xenografts (ER positive MCF-7 and ER negative MT-1)implanted in nude mice. At a dose of 12.5 mg/kg (given i.v.), thealanyl-prodrug of formula (Iw) caused a greater extent of growthretardation than its lysyl—counterpart of formula (Iz) against MCF-7xenografts. Dose-dependent body weight loss was observed with thecompound of formula (Iz). In the MT-1 xenografts, the compound offormula (Iw) was toxic at 25 mg/kg, while the compound of formula (Iz)was toxic at both doses of 12.5 mg/kg and 25 mg/kg; moderate tumorgrowth inhibition was observed in surviving mice treated with eitherprodrug.

In the accompanying drawings there are illustrated typical results oftumour growth inhibition in tumour xenographs following drug treatmentas detailed below.

Tumour growth inhibition observed with MCF7 xenografts treated with thecompound 2-(4′-amino-3′-methylphenyl)benzothiazole (designated DF203)and compound Ik (conveniently designated 5F203) is shown in FIG. 1 ofthe accompanying drawings. In FIG. 2 of said drawings there is shown thetumour growth inhibition observed with COLO205 xenografts treatedrespectively with the alanyl prodrug form of DF203 (compound Iv), the 5Fanalogue of DF203 (compound Ik), and with the 6F analogue of DF203(compound Ib).

Pharmacokinetic Studies

Although amino acid amide prodrug compounds such as those of formulae(Iw), (Iz) and (Iad) in the form of their hydrochloride salts have beenfound to be stable in rat and other mammalian plasma in vitro, it hassurprisingly been found that these prodrugs are readily removed fromsuch plasma and reconverted to their parent compound in vivo, e.g. whengiven to rats intravenously (i.v.) at a typical dose of 25 mg/kg,thereby demonstrating suitability for use as prodrugs.

By way of example, TABLE 2 below shows the plasma concentrationsmeasured following administration to mice at a dose of 70 μmol/kg of5F203 (compound Ik) and the lysyl prodrug analogue thereof in the formof its dihydrochloride salt (compound Iad). A similar progressiveincrease in concentration of the parent compound 5F203 has also beenobserved following addition of said lysyl prodrug analogue of 5F203(compound lad) to a culture of MCF-7 cells.

TABLE 2 Geometric Mean Mean Sample Time Plasma Concentration (μM) (min)Compound Iad Compound Ik 3.5 23.67  1.18 6.5 7.35 1.53 9.5 5.05 1.8412.5 3.47 2.27 15.5 3.33 3.27 20.8 2.80 2.68 30.5 2.24 3.77 45.4 1.163.41 60.5 1.25 4.11 90.6 1.06 3.52 120.5 0.41 2.63 240.0 0.08 1.00 360.0bld 0.59Preparative Methods

In most cases the compounds of formula (I) of the present invention canreadily be synihesised by various routes from easily available startingmaterials. By way of example, several such general synthetic routes,designated Route A, Route B, Route C, Route D and Route E are describedbelow. The substituents for the starting materials and products of thesesynthetic routes have the meanings given above in connection with thedefinition of the compound of general formula (I) unless otherwisestated.Route A

In the general method (Jacobsen cyclisation method) for Route A which issuitable when X=S, the starting material is the appropriate substitutedthioberzanilide which may be prepared by reacting an optionallysubstituted 4-nitrobenzoyl chloride with a solution of the appropriatelysubstituted fluoroanilinc and subsequently treating the oxybenzanilideproduct with Lawesson's reagent to form the thiobenzanilide. In atypical procedure, this thiobenzanilide (1 Mol. equiv.) is finelypowdered and mixed with a little ethanol to form a wet paste. A 30% w/vsolution of aqueous sodium hydroxide (8 Mol. equiv.) is added anddiluted with water to form a suspension/solution of the thiobenzanilidein 10% w/v aqueous sodium hydroxide. Aliquots of thissuspension/solution are then introduced dropwise at one minute intervalsinto a stirred solution of potassium ferricyanide (4 Mol. equiv.) inwater at 80-90° C. The reaction mixture is heated for a further 30minutes, then cooled. The product is collected, washed with water andcrystallised. Further reduction, e.g. by heating under reflux withtin(II) chloride dihydrate in ethanol solvent, yields a compound offormula (I) wherein R⁵ and R⁶ each represent hydrogen. Methods wellknown in the art may be used to prepare further compounds of formula (I)where R⁵ and/or R⁶ do not represent hydrogen.Route B

In the so-called Disulphide general method of Route B which is alsosuitable when X=S, typically the disulphide starting material is addedtogether with tin(II) chloride to a solution of conc HCl, ethanol andwater. The reaction mixture is heated under reflux for 15 hours, cooledto 25° C. and poured into water. Sodium hydroxide is added slowly, andthe mixture stirred for 60 minutes. The precipitate is filtered fromsolution, and washed with water to leave a solid which is purified bycolumn chromatography (dichloromethane) followed by recrystallisationfrom ethanol to give clear needles. A particular example of the use ofthis Disulphide Route including preparation of the disulphide startingmaterial is hereinafter more fully described in relation to EXAMPLE 11.Route C

In the general method for Route C, sodium hydride (1.1 mol. equiv) isslowly added to a solution of starting material (1.0 mol. equiv) inN-methyl-2-pyrrolidinone (NMP) at room temperature with stirring. Themixture is heated at 150° C. for one hour then allowed to cool. Water(50 ml) is then added and the precipitate collected by filtration anddried in vacuo to give the solid product.

Reduction, e.g. by refluxing with tin(II) chloride in ethanol, vields acompound of formula (I) wherein R⁵ and R⁶ each represent hydrogen.Methods well known in the art may be used to prepare further compoundsof formula (I) where R⁵ and/or R⁶ do not represent hydrogen.

This method is generally applicable but is especially useful for thesynthesis of compounds with 7-fluoro, 5-fluoro, 5,6-difluoro and6,7-difluoro substituents.Route D

Route D is for 3′-halogenation of compounds of formula (I). The generalmethods for each variant are as follows:

-   (i) in the general method for iodination, iodine monochloride ICl is    added to a solution of the starting material in acetic acid at    25° C. The resulting solution is stirred for 2 hours, then the    solvent is removed under vacuum. The residue is dissolved in    chloroform and washed with aqueous sodium carbonate, aqueous sodium    thiosulfate and water. Evaporation of the solvent, is followed by    column chromatography (chloroform) and recrystallisation from    methanol giving needles.-   (ii) in the general method for chlorination, a solution of the    3′-iodo compound prepared as in (i) above and copper(I) chloride in    DMF is heated under reflux overnight. After cooling, the reaction    mixture is poured into ethyl acetate, the precipitated solids are    filtered off and the resulting solution evaporated to dryness. The    product is purified by column chromatography (dichloromethane)    followed by recrystallization from methanol to give a pale green    solid.-   (iii) in the general method for bromination, bromine is added to a    solution of the original starting material in dichloromethane at    10° C. The resulting solution is stirred for 10 min, then poured    into water/ice. The organic layer is removed and washed with 10%    sodium thiosulfate, water and evaporated. The product is purified by    column chromatography (dichloromethane) to leave a white solid.    Route E

Route E is for preparing amino acid prodrug derivatives.

A compound of formula (I) wherein R⁶ represents hydrogen (7.75 mmol) isdissolved tri dichloromethane (100 ml) and stirred at room temperature.To this solution is added 1-ethyl-3-(3′-dimethylaminopropyl)carbodiimidehydrochloride (2.3 mmol), HOBt (2.3 mmol) and the appropriate BOCprotected amino acid (2.3 mmol). This procedure is repeated and thereaction is continued until a clear solution is obtained. The solvent isremoved under vacuum and the resulting oil purified by columnchromatography (2% methanol/dichloromethane). Recrystallisation fromethanol gives a white solid.

The BOC protected amino acid derivative thus obtained (3.5 mmol) isdissolved in dichloromethane (20 ml). Dry HCl gas is bubbled through thesolution to saturate it, then the reaction mixture is stirred for afurther 2 hrs at 25° C. The precipitate is filtered from solution andwashed with dichloromethane (10 ml), to leave a bright yellowcrystalline solid. Recrystallisation, if required, is carried out usingmethanol/acetolle.

Therapeutic Use

As already indicated, compounds of this invention have been found toinhibit tumor cell proliferation and to have significant selectiveantitumor activity. Antitumor activity may be evidenced by reduction oftumor cell number in mammals bearing cancer tumors, e.g. breast cancertumors, and a consequent increase in survival time as compared to acontrol provided by animals which are untreated. Antitumor activity isfurther evidenced by measurable reduction in the size of solid tumorsfollowing treatment with the compounds of this invention compared to thetumors of untreated control animals.

Accordingly, as previously stated the compounds of the present inventionare of particular interest for the treatment of a range of selectedcancer tumors, and the invention further provides a method for thetreatment of a patient suffering from certain kinds of cancer. For thispurpose, a therapeutically effective non-toxic amount of a compound offormula (I) as hereinbefore defined, may be suitably administered,orally, parenterally (including subcutaneously, intramuscularly andintravenously), or topically. The administration will generally becarried out repetitively at intervals, for example once or several timesa day.

The amount of the compound of formula (I) which is required in order tobe effective as an antitumor agent for treating mammals will of coursevary and is ultimately at the discretion of the medical or veterinarypractitioner treating the mammal in each particular case. The factors tobe considered by such a practitioner, e.g. a physician, include theroute of administration and pharmaceutical formulation; the mammals bodyweight, surface area, age and general condition; and the chemical formof the compound to be administered. However, a suitable effectiveantitumor dose may be in the range of about 1.0 to about 75 mg/kgbodyweight, preferably in the range of about 5 to 40 mg/kg with mostsuitable doses being for example in the range of 10 to 30 mg/kg. Indaily treatment for example, the total daily dose may be given as asingle dose, multiple doses, e.g. two to six times per day, or byintravenous infusion for any selected duration. For example, in the caseof a 75 kg mammal, the dose range could be about 75 to 500 mg per day,and it is expected that a typical dose would commonly be about 100 mgper day. If discrete multiple doses are indicated, treatment mighttypically be 50 mg of the compound of formula (I), given 4 times per dayin the form of a tablet, capsule, liquid (e.g. syrup) or injection.

While it may be possible for the compounds of formula (I) to beadministered alone as the raw chemical, it is preferable to present thecompounds as a pharmaceutical formulation. Formulations of the presentinvention, for medical use, will generally comprise the compound offormula (I) together with one or more pharmaceutically acceptablecarriers and, optionally, any other therapeutic ingredients. Thecarrier(s) must be pharmaceutically acceptable in the sense of beingcompatible with the other ingredients of the formulation and notdeleterious to the recipient thereof.

The present invention therefore further provides a pharmaceuticalformulation comprising a compound of formula (I) together with apharmaceutically acceptable carrier thereof.

The possible formulations include those suitable for oral, rectal,topical and parenteral (including subcutaneous, intramuscular andintravenous) administration or for administration to the lung or anotherabsorptive site such as the nasal passages.

All methods of formulation will generally include the step of bringingthe compound of formula (I) into association with a carrier whichconstitutes one or more accessory ingredients. Usually, the formulationsare prepared by uniformly and intimately bringing the compound offormula (I) into association with a liquid carrier or with a finelydivided solid carrier or with both and then, if necessary, shaping theproduct into desired formulations.

Formulations of the present invention suitable for oral administrationmay be presented as discrete units such as capsules, cachets, tablets orlozenges, each containing a predetermined amount of the compound offormula (1); as a powder or granules; or a suspension in an aqueousliquid or non-aqueous liquid such as a syrup, an elixir, an emulsion ora draught. The compound of formula (I) may also be presented as a bolus,electuary or paste.

A tablet may be made by compression or moulding, optionally with one ormore accessory ingredients. Compressed tablets may be prepared bycompressing, in a suitable machine, the compound of, formula (I) in afree-flowing form such as a powder or granules, optionally mixed with abinder, lubricant, inert diluent, surface active or dispersing agent.Moulded tablets may be made by moulding, in a suitable machine, amixture of the powdered compound of formula (I) with any suitablecarrier.

A syrup may be made by adding the compound of formula (I) to aconcentrated, aqueous solution of a sugar, for example sucrose, to whichmay be added any desired accessory ingredient. Such accessoryingredient(s) may include flavourings, an agent to retardcrystallisation of the sugar or an agent to increase the solubility ofany other ingredient, such as a polyhydric alcohol, for example glyerolor sorbitol.

Formulations for rectal administration may be presented as a suppositorywith a usual carrier such as cocoa butter.

Formulations suitable for parental administration conveniently comprisea sterile aqueous preparation of the compound of formula (I) which ispreferably isotonic with the blood of the recipient. An injectableformulation may be made up for example with the compound2-(4′-amino-3′-methylphenyl)-5-fluorobenzothiazole in the form of awater-soluble lysyl amide dihydrochloride salt dissolved in saline withTween 80™ (0.05%) or 5% dextrose in water. A typical dose range in thiscase for use in treating humans would be 1-100 mg/m².

In addition to the aforementioned ingredients, formulations of thisinvention, for example ointments, creams and the like, may include oneor more accessory ingredients, for example a diluent, buffer, flavouringagent, binder, surface active agent thickener, lubricant and/or apreservative (including an antioxidant) or other pharmaceutically inertexcipient.

The compounds of this invention may also be made up for administrationin liposomal formulations which can be prepared by methods well-known inthe art.

Thus, as already indicated, the invention also comprises use of acompound of formula (I) as herein defined for the manufacture of amedical preparation, especially for use in the treatment of cancer.

EXAMPLES

The preparation of a number of particular compounds which are consideredto be of especial interest for use as active therapeutic substances toinhibit proliferation of at least certain cancer cells and which provideexamples of preferred embodiments of the invention (or examples ofreference compounds for comparison purposes) will now be described inmore detail, together with some general procedures for specific types ofreactions. Some of the compounds described can also be useful asintermediates for the preparation of compounds of other embodiments. Thecompound or formula reference codes used elsewhere in this descriptionare also quoted where applicable. It should be understood, however, thatthese specific examples are not intendedto be construed in any way aslimiting the scope of the invention.

Example 1 4-Fluoro-2-4′-amino-3′-methylphenyl)benzothiazole (Ia)

3-Methyl4-nitrobenzoyl chloride (0.2 mol) was added slowly to a solutionof 2-fluoroaniline (0.2 mol) in pyridine (100 ml). The resultingsolution was heated under reflux for 60 min, then poured into water (300ml). The precipitate was filtered from solution, washed with water (100ml), followed by methanol to afford a white solid.

Lawesson's reagent (0.07 mol) was added to a solution of the benzanilideobtained (0.1 mol) in HMPA (50 ml). The resulting solution was heated at100° C. for 15 hr, then poured into water (300 ml). The product wasextracted into diethyl ether (3×300 ml) and washed with water (3×200ml). Evaporation of the solvent followed by recrystallization frommethanol gave a bright orange solid.

A solution of the fluoro substituted thiobenzanilide thus obtained (0.2mol) in aqueous sodium hydroxide (1.8 mol in 50 ml water) containingethanol (5 ml) was added dropwise to a solution of potassiumferricyanide (0.8 mol) in water (20 ml) at 90° C. over a period of 60min. The resulting solution was stirred at 90° C. for a further 2 hr,then cooled in ice. The precipitate was filtered from solution andwashed with water (100 ml). The product: was purified by columnchromatography (30% hexane/chloroform) to leave a bright yellow solid.

The product of the previous step (0.03 mol) and tin(II).chloridedihydrate (0.15 mol) were suspended in ethanol (150 ml) and heated underreflux for 2 hrs. The solvent was removed under vacuum and the resultingoil taken up in ethyl acetate (700 ml). The organic layer was washedwith 2 M sodium hydroxide (2 ×200 ml), water (100 ml) and salt brine (30ml). Removal of the solvent under vacuum followed by recrystallizationfrom methanol gave the title compound as a pale yellow solid.

mp 203-205° C.; IR 3491, 3369 (NH₂), 1624 (C═N) cm⁻¹; ¹H NMR (DMSO-d6) δ7.86 (1H, dd, J 1.5, 8.5 Hz, H-7), 7.71 (1H, d, J2 Hz, H-2′), 7.66 (1H,dd, J 2, 8.25 Hz H-6′), 7.37-7.30 (2H, m, H-5, H-6), 6.73 (1H, d, J8.25, H-5′), 5.78 (2H, brs, NH₂), 2.17 (3H, s, CH₃); MS (CI) m/z 259.5(M+1); Anal (C₁₄H₁₁N₂SF) C, H, N.

EXAMPLE 2 6-Fluoro-2-(4′-amino-3′-methylphenyl)benzothiazole (Ib)

The method of Example 1 was carried out using 4-fluoroaniline instead of2-fluoroaniline. The title compound was obtained as a pale yellow solid.

mp 203-205° C.; IR 3467, 3306 (NH₂), 1604 (C═N) cm⁻¹.

Example 3 4-Fluoro2-(4-aminophenyl)benzothiazole (Ic)

The method of Example 1 was carried out using 4-nitrobenzoyl chlorideinstead of 3-methyl-4-nitrobenzoyl chloride. The title compound wasobtained as a pale yellow solid.

mp 219-221° C.; IR 3456, 3350 (NH₂), 1604 (C═N) cm⁻¹.

Example 4 6-Fluoro2-(4′-aminophenyl)benzothiazole (Id)

The method of Example 1 was carried out using 4-nitrobenzoyl chlorideinstead of 3-methyl-4-nitrobenzoyl chloride and 4-fluoroaniline insteadof 2-fluoroaniline. The title compound was obtained as a pale yellowsolid.

mp 152-155° C.; IR 3333, 3219 (N₂), 1604 (C═N) cm⁻¹.

Example 5 4,5-Difluoro-2-(4′-amino-3′-methylphenyl)benzothiazole (Ie)

The method of Example 1 was carried out 2,3-difluoroaniline instead of2-fluoroaniline. The title compound was obtained as a pale yellow solid.

mp 204-205° C.; IR 3466, 3387 (NH₂), 1616 (C═N) cm⁻¹.

Example 6 4,6Difluoro-244′-amino-3′-methylphenyl)benzothiazole (If)

The method of Example 1 was carried out using 2,4-difluoroariflineinstead of 2-fluoroaniline. The title compound was obtained as a paleyellow solid.

mp 197-199° C.; IR 3475, 3385 (NH₂), 1622 (C═N) cm⁻¹.

Example 7 5,7-Difluoro-2-(4′-amino3′-methylphenyl)benzothiazole (Ig)

The method of Example 1 was carried out using 3,5-fluoroaniline insteadof 2-fluoroaniline. The title compound was obtained as a pale yellowsolid.

mp 201-203° C.; IR 3483, 3323 (NH₂), 1616 (C═N) cm⁻¹.

Example 8 7-Fluoro-2-(4′-imino-3′-methylphenyl)benzothiazole (Ih)

This Example made use of the general preparative method designated RouteC. 3-Methyl4-nitrobenzoyl chloride (0.2 mol) was added slowly to asolution of 2-bromo-3-fluoroaiiiline (0.2 mol) in pyridine (100 ml). Theresulting solution was heated under reflux for 60 min, then poured intowater (300 ml). The precipitate was filtered from solution, washed withwater (100 ml), followed by methanol to afford a white solid.

Lawesson's reagent (0.07 mol) was added to a solution of the benzanilideobtained (0.1 mol) in HMPA (50 ml). The resulting solution was heated at100° C. for 15 hr, then poured into water (300 ml). The product wasextracted into diethyl ether (3×300 ml) and washed with water (3×200ml). Evaporation of the solvent followed by recrystallization frommethanol gave a bright orange solid.

Sodium hydride (0.22 mol) was slowly added to a solution of the fluorosubstituted thiobenzanilide thus obtained (0.2 mol) inN-methyl-2-pyrrolidinone (2 mol) at room temperature with stirring. Themixture was heated at 150° C. for one hour then allowed to cool. Water(50 ml) was then added and the precipitate collected by filtration anddried in vacuo to give the product as a white solid.

The product of the previous step (0.03 mol) and tin(II) chloridedihydrate (0.15 mol) were suspended in ethanol (150 ml) and heated underreflux for 2 hours. The solvent was removed under vacuum and theresulting oil taken up in ethyl acetate (700 ml). The organic layer waswashed with 2 M sodium hydroxide. (2×200 ml), water (100 ml) and saltbrine (30 ml). Removal of the solvent under vacuum followed byrecrystallization from methanol gave the title compound as a pale yellowsolid.

mp 175-177° C.; IR 3021, 1621 (C═N), 1470, 1215, 750 cm⁻¹.

Example 9 5,6-Difluoro-2-(4′-amino-3′-methylphenyl)benzothiazole (Ii)

The method of Example 8 was carried out using 2-bromo4,5-difluoroanilineinstead of 2-bromo-3-fluoroaniline. The product was obtained as a paleyellow solid.

mp 226-228° C.; IR 3497, 3333, 1.632, 1466, 1454, 1406, 1314, 1142 cm⁻¹.Example 10

6,7-Difluoro-2-(4′-amino3′-methylphenyl)benzothiazole (Ij)

The method of Example 8 is carried out using 2-bromo-5,6difluoroanilineinstead of 2-bromo-3-fluoroaniline.

Example 11 5-Fluoro-2-(4′-amino-3′-methylphenyl)benzothiazole (Ik)

“Disulphide Route”

2-Amino-5-fluorobenzothiazole (5 g, 0.03 mol) was added to a solution ofpotassium hydroxide (25 g) in water (50 ml). The resulting mixture washeated under reflux for 5 hr, after which complete solution hadoccurred. After cooling, the reaction mixture was made acidic (pH 6) bythe addition of acetic acid. A further portion of water (50 ml) wasadded and the resulting mixture stirred overnight. The solid precipitatewas filtered from solution and recrystallized from ethanol/water to givebis-2-amino-5-fluorophenyl) disulphide as a pale yellow solid.

3-Methyl4-nitrobenzoyl chloride (1.45 g, 7.3 mmol) was added to asolution of bis-(2-amino-5-fluorophenyl) disulfide (1 g, 3.65 mmol) inpyridine (10 ml). The resulting mixture was heated under reflux for 30min. then poured into water (50 ml). The precipitate was filtered fromsolution, and washed with water (50 ml) to leavebis-[2-(3′-methyl4′-nitrobenzanilide)-5-fluorophenyl] disulfide as apale yellow solid.

Then, as described in relation to the preparative method designatedRoute B, to a solution of conc HCl (10 ml), ethanol (20 ml) and water (2ml) was added the bis-[2-(3′-methyl-4′-nitrobenzanifide)-5-fluorophenyl]disulfide (1 g, 1.6 mmol) together with tin(II) chloride (1.86 g, 9.8mmol). The reaction mixture was heated under reflux for 15 hr, cooled to25° C. and poured into water (75 ml). Sodium hydroxide (2 g) was addedslowly, and the mixture stirred for 60 min. The precipitate was filteredfrom solution, and washed with water (10 ml) to leave a yellow solidwhich was purified by column chromatography (dichloromethane) followedby recrystallization from ethanol to give colorless needles.

mp 195-196° C.; IR 3433, 3302 (NH₂), 1622 (C═N) cm⁻¹.

Example 12 5-Fluoro-2-(4′-aminophenyl)benzothiazole (II)

4-Nitrobenzoyl chloride (1.35 g, 7.3 mmol) was added to a solution ofbis-(2-amino-5-fluorophenyl) disulfide prepared as described in Example11 (1 g, 3.65 mmol) in pyridine (10 ml). The resulting mixture washeated under reflux for 30 min, then poured into water (50 ml). Theprecipitate was filtered from solution, and washed with water (50 ml) toleave bis-[2-(4′-nitrobenzanilide)-5-fluorophenyl] disulfide as a paleyellow solid.

To a solution of conc HCl (10 ml), ethanol (10 ml) and water (2 ml) wasadded bis-[2-(4′-nitrobenzanilide)-5-fluorophenyl] disulfide (1 g, 1.7mmol) and tin(II) chloride (1 g, 5.2 mmol). The reaction mixture washeated under reflux for 15 hr, cooled to 250° C. and poured into water(75 ml). Sodium hydroxide (2 g) was added slowly, and the mixturestirred for 60 min. The precipitate was filtered from solution, findwashed with water (10 ml) to leave a yellow solid which was purified bycolumn chromatography (dichloromethane) followed by recrystallizationfrom ethanol to give colorless needles.

mp 153-155° C.; IR 3460, 3290 (NH₂), 1637 (C═N) cm⁻¹.

Example 13 4-Fluoro-2-(4′-amino-3′-iodophenyl)benzothiazole (Im)

A solution of the 4-fluoro-2-(4′-aminophenyl)benzothiazole prepared asdescribed in Example 3 (4.5 mmol) in acetic acid (20 ml) was addeddropwise to a solution of iodine monochloride (5.8 mmol) in acetic acid(20 ml) at 25° C. The resulting solution was stirred for 2 hr, then thesolvent was removed under vacuum. The residue was dissolved inchloroform (100 ml) and washed with aqueous sodium carbonate (50 ml),aqueous sodium thiosulfate (50 ml) and water (50 ml). Evaporation of thesolvent, followed by column chromatography (chloroform) andrecrystallization from methanol gave pale cream needles.

mp 210-211° C.; IR 3474, 3377 (NH₂), 1610 (C═N) cm⁻¹.

Example 14 5-Fluoro-2-(4′-amino-3′-iodophenyl)benzothiazole (In)

The method of Example 13 was carried out using the5-fluoro-2-(4′-aminophenyl)benzothiazole prepared as described inExample 12 instead of 4-fluoro-2-(4′-aminophenyl) benzothiazole.

mp 187-188° C.; IR3447, 3317 (NH₂), 1612 (C═N) cm⁻¹.

Example 15 6-Fluoro-2-(4′-amino-3′-iodophenyl)benzothiazole (Io)

The method of Example 13 was carried out using the6-fluoro-2-(4′-aminophenyl)benzothiazole prepared as described inExample 4 instead of 4-fluoro-2-(4′-aminophenyl) benzothiazole.

mp 198-200° C.; IR 3445, 3290 (NH₂), 1620 (C═N) cm⁻¹.

Example 16 4-Fluoro-2-(4′-amino-3′-chlorophenyl)benzothiazole (Ip)

A solution of the 4-fluoro substituted2-(4′-amino-3′-iodophenyl)benzothiazole prepared as described in Example13 (1.35 mmol) and copper(I) chloride (6.75 mmol) in DMF (5 ml) washeated under reflux overnight. After cooling, the reaction mixture waspoured into ethyl acetate (100 ml), the precipitated solids werefiltered off and the resulting solution evaporated to dryness. Theproduct was purified by column chromatography (dichloromethane) followedby recrystallization from methanol to give a pale green solid.

mp 181-1830° C.; IR 3477, 3381 (NH₂), 1620 (C═N) cm⁻¹.

Example 17 5-Fluoro-2-(4′-amino-3′-chlorophenyl)benzothiazole (Iq)

The method of Example 16 was carried out using the 5-fluoro substituted2-4′-amino-3′-iodophenyl)benzothiazole prepared as described in Example14 instead of 4-fluoro substituted2-(4′-amino-3′-iodophenyl)benzothiazole.

mp 177-178° C.; IR 3481, 3369 (NH₂), 1631 (C-N) cm⁻¹.

Example 18 6-Fluoro-2-(4′-amino3′chlorophenYl)bcnzothiazole (Ir)

The method of Example 16 was carried out using the 6-fluoro substituted2-(4′-amino-3′-iodophenyl)benzothiazole prepared as described in Example15 instead of 4-fiuoro substituted2-(4′amino-3′-iodophenyl)benzothiazole.

mp 194-1950° C.; IR 3472, 3310 (NH₂), 1628 (C═N) cm⁻¹.

Example 19 4-Fluoro-2-(4′amino-3′-bromophenyl)benzothiazole (Is)

Bromine (0.8 mmol) was added to a solution of the4-fluoro-2-(4′-aminophenyl) benzothiazole prepared as described inExample 3 (0.8 mmol) in dichloromethane (20 ml) at 10° C. The resultingsolution was stirred for 10 min, then poured into water/ice (10 ml). Theorganic layer was removed and washed with 10% sodium thiosulfate (10ml), water (10 ml) and evaporated. The product was purified by columnchromatography (dichloromethane) to leave a white solid.

mp 211-213° C.; IR 3416, 3379 (NH₂), 1618 (C═N) cm⁻¹.

Example 20 5-Fluoro-2-(4′-amino-3′-bromophenyl)benzothiazole (It)

The method of Example 19 was carried out using the5-fluoro-2-(4′-aminophenyl) benzothiazole prepared as described inExample 12 instead of 4-fluoro-2-(4′-aminophenyl) benzothiazole.

mp 181-183° C.; IR 3464, 3311 (NH₂), 1612 (C═N) cm⁻¹.

Example 21 6-Fluoro2-(4′-amino-3′-bromophenyl)benzothiazole (Iu)

The method of Example 19 was carried out using the6fluoro-2-(4′-aminophenyl) benzothiazole prepared as described inExample 4 instead of 4-fluoro-2-4′-aminophenyl) benzothiazole.

mp 209-211° C.; IR 3462, 3300 NH₂), 1626 (C═N) cm⁻¹.

Example 22 2-(4′-Aminophenyl)benzothiazole Alanyl Amide HydrochlorideSalt (Iv)

2-(4′-Aminophenyl)benzothiazole (7.75 mmol) was dissolved indichloromethane (100 ml) and stirred at room temperature. To thissolution was added 1-ethyl-3-(3′-dimethylaminopropyl)carbodiimidehydrochloride (2.3 mmol), HOBt (2.3 mmol) and Boc protected alanine (2.3mmol). After stirring for 24 hrs a further 2.3 mmol of each reactant wasadded, and stirring continued for a further 24 hrs. This procedure wasrepeated twice more and stirring continued for a further 3 days, until aclear solution formed. The solvent was removed under vacuum and theresulting oil purified by column chromatography (2%methanol/dichloromethane). Recrystallisation from ethanol gave a whitesolid.

The Boc protected amino acid derivative thus obtained (3.5 mmol) wasdissolved in dichloromeihane (20 ml). Dry HCl gas was bubbled throughthe solution to saturate it, then the reaction mixture was stirred for afurther 2 hrs at 25° C. The precipitate was filtered from solution andwashed with dichloromethane (10 ml), to leave a bright yellowcrystalline solid.

mp 258-259° C.; MS (AP) m/z 298 (M+1).

Example 23 2-(4′-Amino-3′-methylphenyl)benzothiazole Alanyl AmideHydrochloride Salt (Iw)

The title compound was prepared using the method of Example 22 but with2-(4′-arnino-3′-methylphenyl)benzothiazole instead of2-(4′-aminophenyl)-benzothiazole.

mp 272-274° C.; MS (AP) m/z 312 (M+1).

Example 24 2-(4′-Amino-3′-chlorophenyl)benzothiazole Alanyl AmideHydrochloride Salt

The title compound was prepared using the method of Example 22 but with2-(4′-amino-3′-chlorophenyl)benzothiazole instead of2-(4′-aminophenyl)-benzothiazole.

mp 240-243° C.; MS (AP) m/z 332 (M+1).

Example 25 2-(4′-Aminophenyl)benzothiazole Lysine Amide DihydrochlorideSalt (Iy)

The title compound was prepared using the method of Example 22 but withBOC protected lysine instead of BOC protected alanme.

mp 296-298° C.; MS (AP) m/z 355 (M+1).

Example 26 2-(4′-Amino-3′-methylphenyl)benzothiazole Lysyl AmideDihydrochioride Salt (Iz)

The title compound was prepared using the method of Example 22 but with2-(4′-amino-3′-methylphenyl)benzothiazole instead of2-(4′-amino-phenyl)benzothiazole and BOC protected lysine instead of BOCprotected alanine.

mp 290-293° C.; MS (AP) m/z 369 (M+1).

Example 27 2-(4′-Amino-3′-chlorophenyl)benzothiazole Lysyl AmideDihydrochloride Salt (Iaa)

The title compound was prepared using the method of Example 22 but with2-(4′-amino-3′-chlorophenyl)benzothiazole instead of2-(4′-aminophenyl)-benzothiazole and BOC protected lysine instead of BOCprotected alanine.

mp 278-279° C.; MS (AP) m/z 389 (M+1).

Example 28 2-(4′-Anino-3′-methylphenyl)benzothiazole Seryl AmideHydrochloride Salt (Iab)

The title compound was prepared using the method of Example 22 but with2-(4′-amino3′-methylphenyl)benzothiazole instead of 2-(4′-aminophenyl)benzothiazole and BOC protected serine instead of BOC protected alanine.

mp 265-269 0C.; MS (CI) m/z 328 (M+1).

Example 29 6-Fluoro-2-(4′-amino-3′-Methylphenyl)benzothiazole AlanylAmide Hydrochloride Salt (Iac)

The title compound was prepared using the method of Example 22 but with6-fluoro-2-(4′-amino-3′-methylphenyl)benzothiazole prepared as describedin Example 2 instead of 2-(4′-aminophenyl) benzothiazole.

mp 282-2859° C.; MS (CI) m/z 330.3 (M+1).

Example 30 5-Fluoro-2-(4′-amino-3′-methylphenyl)benzothiazole LysylAmide Dihydrochloride Salt (Iad)

The title compound was prepared using the method of Example 22 but with5-fluoro-2-(4′-amino-3′-methylphenyl)benzothiazole prepared as describedin Example 11 instead of 2-(4′-aminophenyl)benzothiazole and BOCprotected lysine instead of BOC protected alanine.

mp 290-294° C., MS (CI) m/z 387.4 (M+1).

Example 31 6-Fluoro-2-(4′-amino-3′-methylphenyl)benzothiazole LysylAmide Dihydrochloride Salt (Iae)

The title compound was prepared using the method of Example 22 but with6-fluoro-2-4′-amino-3′-methylphenyl)benzothiazole prepared as describedin Example 2 instead of 2-4′-aminophenyl)benzothiazole and BOC protectedlysine instead of BOC protected alanine.

mp 298-303° C.; MS (CI) m/z 387.2 (M+1).

Example 32 5-Fluoro-2-(4′-amino-3′-metbylphenyl)benzothiazole AlanylAmide Hydrochloride Salt (Iaf)

The title compound was prepared using the method of Example 22 but with5-fluoro-2-(4-amino-3′-metylphenyl)benzothiazole prepared as describedin Example 11 instead of 2-(4′-aminophenyl)benzothiazole.

mp 280-284° C.; MS (CI) m/z 330.3 (M+1).

Example 33 5-Fluoro-244′-amino-3′-methylphenyl)benzothiazole GlycylAmide Hydrochloride Salt salt (Iai)

The title compound is prepared using the method of Example 22 but with5-fluoro-2-(4′-amino-3′-methylphenyl)benzothiazole prepared as describedin Example 11 instead of 2-4′-aminophenyl)benzothiazole and with BOCprotected glycine instead of BOC protected alanine.

Example 34 5-Iodo-2-(4′-amino-3′-methylphenyl)benzothiazole (Iak)

This was synthesised via a Jacobson cyclisation reaction from theappropriate benzanilide following the method of Route A and wasseparated from the 7-iodo isomer by column chromatography (25% hexanedichloromethane) prior to reduction of the nitro group to amine.

Yield=92%; mp 200-202° C.; IR 3429, 3288 cm⁻¹; MS (CI) m/z 367.1 (M+1).

This compound can also be prepared from the appropriate 3-iodoanilineusing the “Disuiphide Route” previously referred to.

Example 35 7-Iodo-2-(4′-amino-3′-methylphenyl)benzothiazole (Ial)

This was synthesised via Jacobson cyclisation, as above. It wasseparated from the 5-iodo isomer by column chromatography (25%hexane/dichloromethane) prior to reduction of the nitro group to amine.

Yield=93%; mp) 158-159° C.; IR 3477, 3306 cm⁻¹; MS (CI) m/z 366.9 (M+1).

Example 36 5-Fluoro-2-(4′-acetamido-3′-methylphenyl)benzothiazole (Iam)

Acetyl Chloride (0.09g, 1.55 mmol) was added to a solution of5-fluoro2-(4′-amino-3′-methylphenyl)benzothiazole (0.2 g, 0.78 mmol) inchloroform (5 ml) containing triethylamine (86 mg, 0.85 mmol). Theresulting solution was stirred for 30 min, then poured into water (20ml). The organic layer was removed, dried (Na₂SO₄) and evaporated.Recrystallisation from ethanol gave a white solid.

Yield=86%; mp 219-221° C.; MS (CI) m/z 301.3 (M+1).

Example 37 5-Fluoro-2-(4′-amino-3′-cyanophenyl)benzothiazole (Ian)

5-Fluoro-2-(4′-amino-3′-iodophenyl)benzothiazole (5 g, 0.0135 mol),copper cyanide (3.65 g, 0.04 mol) and DMF (100 ml) were heated underreflux for 6 hrs, cooled and the solvent removed under vacuum. Theresidue was stirred in water (50 ml) for 30 mins, then the productextracted with ethyl acetate (2×100 ml). The combined extracts weredried (Na₂SO₄), evaporated and the residue recrystallised from ethanolto give a white solid.

Yield=88%; mp 268-270° C.; IR 3464, 3369, 2218 (CN) cm⁻¹; MS (CI) m/z270.1 (M+1).

Example 38 4Fluoro-2-(4′-amnino-3′-cvanophenyl)benzothiazole (Iao)

This was synthesised from4-fluoro-2-(4′-amino-3′-iodophenyl)benzothiazole by a method analogousto that used for 5-fluoro-2-(4′-amino-3′-cyanophenyl)benzozole.

Yield=18%; mp 225-227° C.; IR 3471, 3366, 2216 (CN), 1642 cm⁻¹; MS (CI)m/z 270 (M+1).

Example 39 6Fluoro-2-(4′-aino-3′-cyanophenyl)benzothiazole (Iap)

This was synthesised from6-fluoro-2-(4′-amino-3′-iodophenyl)benzothiazole by a method analogousto that used for 5-fluoro-2-(4′-amino-3′-cyanophenyl)benzothiazole.

Yield=12%; mp 258-260° C.; IR 3412, 2216 (CN), 1642 cm⁻¹; MS (CI) m/z270 (M+1).

Example 40 5-Fluoro-2-(4′-amino-3′-(hydroxymethyl)phenyl)benzothiazole(Iaq)

5-Fluoro-2-(4′-amino-3′-cyanophenyl)benzothiazole (1 g, 3.75 mmol) wasdissolved in 80% sulfuric acid (50 ml) and heated at 100° C. for 2 hrs.After cooling, the reaction mixture was diluted with water (100 ml) andthe pH adjusted to 7.5 using 50% sodium hydroxide. The product wasextracted with ethyl acetate(3×50 ml), the extracts dried (Na₂SO₄) andevaporated to leave a yellow solid which was taken up in THF (20 ml) andadded dropwise to a solution of LiAlH₄ (0.7 g, 0.019 mol) in THF (15ml). After stirring at 25° C. for 2 hrs, water (20 ml) was added and theproduct extracted with ethyl acetate (3×50 ml). The organic extractswere washed with brine (10 ml), dried (Na₂SO₄) and evaporated. Theresidue was purified by column chromatography (10% ethylacetate/dichloromethane) to leave a yellow powder.

Yield=34%; mp 242-245° C.; IR 3379, 3333, 1448 cm⁻¹; MS (CI) m/z 275.1(M+1).

Example 41 5,6-Difluoro-2-(4′-amino-3′-methylphenyl)benzothiazole AlanyAmide Hydrochloride Salt (Iar)

Synthesised by same method as 5-fluoro analogue (Iaf).

Yield=96%; mp 268-270°C.; MS (CI) m/z 348.0 (M+1).

Example 42 5,6-Difluoro-2-(4′-amino-3′-methylphenyl)benzothiazole LysylAmide Dihydrochloride (Ias)

Synthesised by same method as 5-fluoro analogue (Iad).

Yield=74%; mp 278-281° C.; MS (CI) m/z 405.0 (M+1).

Example 43 5-Trimethylstannyl-2-(4′-amino-3′-methylphenyl)benzoihiazole(Iat)

5-Iodo-2-(4′-amino-3′-methylphenyl)benzothiazole (Compound Iak) (1.4 g,4.12 mmol) and tetralas triphenylphosphine palladium (48 mg, 0.41 mmol)were dissolved in dioxane (20 ml) and placed under nitrogen.Hexamethylditin (5 g, 0.15 mol) was added and the resulting solutionheated under reflex for 4 hrs. The precipitated palladium was filteredfrom solution and washed with ethyl acetate (50 ml). The organicfractions were evaporated and chromatographed (chloroform) to leave awhite waxy solid. Recrystallisation from ethanol gave clear needles.

Yield=85%; mp 158-160° C.; MS (CI) m/z 402.8, 403.4, 404.9, 405.5 (M+1).

Example 44 5-¹⁸Fluoro-2-(4′-amino-3′-methylbenzothiazole)

The compound Iat of Example 44 can be used as an intermediate in thepreparation of the above ¹⁸F labelled 5-fluoro compound from thecorresponding 5-iodo substituted compound mentioned earlier. In thiscase the compound Iat is reacted at −20° C. with (CF₃CO)₂O in thepresence of Na₂CO₃ and CH₂Cl₂ to form the trifluoroacetyl derivativewhich is then converted into the title compound by reacting with ¹⁸Facetyl hypofluorite followed by acid hydrolysis. The overall scheme isdepicted in the diagram below.

Of the compounds described above, the compound5-fluoro-2-(4′-amino-3′-methylphenyl)benzothiazole Ik and its lysylamino acid amide prodrug Iad, in the form for instance of its watersoluble dihydrochloride salt prepared as in Example 30 from its parentcompound, are of especial interest for clinical use as effectiveantitumour agents. The solubility of this particular prodrug Iad inwater and its chemical robustness makes it very suitable for parenteraladministration as an injectable formulation, sterilised by filtration,after which it becomes converted in vivo to the 5-fluoro substitutedcompound Ik.

As an alternative to the “disulphide” preparative method described forcompound Ik in Example 11, it may also be prepared by a “RegiospecificCyclisation” Route involving in part the general method of Route C. Boththese schemes are illustrated in the diagram below, together with thescheme for converting the compound Ik into the prodrug Iad.

As will be seen, the invention presents a number of different aspectsand it should be understood that it embraces within its scope all noveland inventive features and aspects herein disclosed, either explicitlyor implicitly and either singly or in combination with one another. Thisincludes the methods or processes for preparing or synthesising thecompounds referred to. It will, however, also be understood that manydetailed modifications are possible and, in particular, the scope of theinvention is not to be construed as being limited solely by theillustrative example(s) or by the terms and expressions used hereinmerely in a descriptive or explanatory sense.

TABLE 1 In vitro activity (IC₅₀ concentration in nM) of variouscompounds of Formula (I) (I)

wherein p = O, X = S, Q is a direct bond; R³ = H, Y = O, R⁷ =—CH(R⁸)NH₃Cl IC₅₀ in IC₅₀ in Compound n R¹ R² R⁵ R⁶ R⁸ MCF-7 MDA468 offormula 1 4-F 3-CH₃ H H <0.1 0.13 Ia 1 6-F 3-CH₃ H H <0.1 0.11 Ib 1 4-FH H H 8.54 29.4 Ic 1 6-F H H H <0.1 48.1 Id 2 4,5-diF 3-CH₃ H H 0.640.67 Ie 2 4,6-diF 3-CH₃ H H <0.1 5.35 If 2 5,7-diF 3-CH₃ H H 0.9 4.4 Ig1 7-F 3-CH₃ H H 2.39 10.35 Ih 2 5,6-diF 3-CH₃ H H <0.1 3.55 Ii 1 5-F3-CH₃ H H <0.1 <0.1 Ik 1 5-F H H H <0.1 <0.1 Il 1 4-F 3-I H H 7.88 9.11Im 1 5-F 3-I H H <0.1 <0.1 In 1 6-F 3-I H H <0.1 <0.1 Io 1 4-F 3-Cl H H0.95 1.93 Ip 1 5-F 3-Cl H H 7.09 18.9 Iq 1 6-F 3-Cl H H 4.08 11.7 Ir 14-F 3-Br H H 38.2 24 Is 1 5-F 3-Br H H <0.1 0.2 It 1 6-F 3-Br H H 45.568.7 Iu 1 5-I 3-CH₃ H H 492.96 80.86* Iak 1 7-I 3-CH₃ H H 28.28 323.11Ial 1 5-F 3-CH₃ H COCH₃ 7.64* 5.84* Iam 1 5-F 3-CN H H <0.1 <0.1 Ian 15-F 3-CH₂OH H H <0.1 0.43 Iaq 0 3-F H H 1.58 33.41 0 H H C(Y)R⁷ CH₃ 6040 Iv 0 3-CH₃ H C(Y)R⁷ CH₃ 360 340 Iw 0 3-CH₃ H C(Y)R⁷ (CH₂)₄NH₂ 80 70Iz 1 6-F 3-CH₃ H C(Y)R⁷ CH₃ 44 297 Iac 1 5-F 3-CH₃ H C(Y)R⁷ (CH₂)₄NH₂ 40158 Iad 1 6-F 3-CH₃ H C(Y)R⁷ (CH₂)₄NH₂ 147.31 328.09 Iae 1 5-F 3-CH₃ HC(Y)R⁷ CH₃ 5.89 37.74 Iaf 2 5,6-diF 3-CH₃ H C(Y)R⁷ CH₃ 33.06 216.9 Iar 25,6-diF 3-CH₃ H C(Y)R⁷ (CH₂)₄NH₂ 30.69 301.87 Ias *IC₅₀ concentration inμM

1. An arylbenzazole compound represented by the structural formula 1below, or a pharmaceutically acceptable salt thereof,

wherein X represents S or O; R¹ independently represents fluoro, iodo ortrimethyltin; R² represents hydrogen, NO₂, N₃, halogen, alkyl, a halosubstituted or hydroxy substituted alkyl, CN or CF₃; R³ representshydrogen, halogen, alkyl, or a halo substituted or hydroxy substitutedalkyl; R⁴ independently represents alkyl, a halo substituted or hydroxysubstituted alkyl, hydroxyl, alkoxy or aralkoxy; R⁵ and R⁶ eachindependently represent hydrogen, an amino acid, an alkyl, or a group

wherein Y represents O or S, and R⁷ represents alkyl or —CH(R⁸)NH₂ whereR⁸ represents hydrogen, or an optionally substituted alkyl; Q representsa direct bond, —CH₂— or —CH═CH—; p represents zero, 1 or 2; and nrepresents zero, 1, 2 or 3; subject to the following provisos: (a) alkylor substituted alkyl groups include linear, branched or cyclicstructures but when present as linear or branched structures in thecompound or as a moiety in another group such as alkoxy they arecomposed of less then ten carbon atoms; (b) p represents zero or 1 whenn represents 3; (c) when N represents zero, at least one of R⁵ or R⁶represents —C(Y)—CH(R⁸)NH₂; (d) when a group is optionally substituted,unless otherwise specified, the substituent is selected from one or moreof the following: a halogen, OH, SH, NH₂, COOH and CONH₂.
 2. Anarylbenzazole compound of claim 1 with at least one the followingfeatures: (a) alkyl groups when present as such or as a moiety in othergroups such as alkoxy each contain less than six carbon atoms; (b) atleast some alkyl groups when present as such or as a moiety in ethergroups such as alkoxy are methyl or ethyl; or (c) halogen substitutents,when present, are selected from fluorine, iodine, bromine and chlorine.3. An arylbenzazole compound of claim 2 where the halogen substituent isfluorine.
 4. An arylbenzazole compound of claim 3 wherein said fluorinesubstituent is the isotope ¹⁸F.
 5. An arylbenzazole compound of claim 1or 2 wherein R¹ is fluorine.
 6. An arylbenzazole compound of claim 1wherein R¹ is in the 5-position of the benzazole moiety.
 7. Anarylbenzazole compound of claim 1 wherein R² is a substitutent in the 3′position of the phenyl group.
 8. An arylbenzazole compound of claim 1wherein X is sulphur.
 9. An arylbenzazole compound of claim 1 whereinone of R⁵ and R⁶ is C(Y)—CH(R⁸)NH₂ or a salt thereof, and the other ishydrogen.
 10. An arylbenzazole compound of claim 1 wherein Y is O and R⁸is selected from hydrogen, —CH₃, —(CH₂)₄NH₂ or —CH₂OH.
 11. Anarylbenzazole compound which is one of the following: 4Fluoro-2-(4′-amino-3′-methylpheyl)benzothiazole; 6 Fluoro2-(4′-amino-3′-phenymetylphenyl)benzothiazole; 4Fluoro-2-(4′-aminophenyl)benzothiazole;6-Fluoro-2-(4-amino)benzothiazole;4,5-Difluoro-2-(4′-amino-3′-methylphenyl)benzothiazole;4,6-Difluoro-2-(4′-amino-3′-methylphenyl)benzothiazole;5,7-Difluoro-2-(4′-amino-3′-methylphenyl)benzothiazole;7-Fluoro-2-(4′-amino-3′-methylphenyl)benzothiazole;5,6-Difluoro-2-(4′-amino-3′-methylphenyl)benzothiazole,6,7-Difluoro-2-(4′-amino-3′-methylphenyl)benzothiazole;5-Fluoro-2-(4′-amino-3′-methylphenyl)benzothiazole;5-Fluoro-2-(4′-aminophenyl)benzothiazole;4-Fluoro-2-(4′-amino-3′-iodophenyl)benzothiazole;5-Fluoro-2-(4′-amino-3′-iodophenyl)benzothiazole;6-Fluoro-2-(4′-amino-3′-iodophenyl)benzothiazole;4-Fluoro-2-(4′-amino-3′-chlorophenyl)benzothiazole;5-Fluoro-2-(4′-amino-3′-chlorophenyl)benzothiazole;6-Fluoro-2-(4′-amino-3′-chlorophenyl)benzothiazole;4-Fluoro-2-(4′-amino-3′-bromophenyl)benozothiazole;5-Fluoro-2-(4′-amino-3′-bromophenyl)benozothiazole;6-Fluoro-2-(4′-amino-3′-bromophenyl)benozothiazole;2-(4″-Aminophenyl)benzothiazole alanyl amide hydrochloride salt;2-(4′-Amino-3′-methylphenyl)benzothiazole alanyl amide hydrochloridesalt; 2-(4-Amino-3′-chlorophenyl)benzothiazole alanyl amidehydrochloride salt; 2-(4′-Aminophenyl)benzothiazole lysyl amidedihydrochloride salt; 2-(4′-Amino-3′-methylphenyl)benzothiazole lysylamide dihydrochloride salt; 2-(4′-Amino-3′-chlorophenyl)benzothiazolelysyl amide dihydrochlonide salt;2-(4′-Amino-3′-methylphenyl)benzothiazole serine hydrochloride salt;6-Fluoro-2-(4′-amino-3′-methylphenyl)benzothiazole alanyl amidehydrochloride salt; 5-Fluoro-2-(4′-amino-3′methylphenyl)benzothiazolelysyl amide dihydrochloride salt;6-Fluoro-2-(4′-amino-3′-methylphenyl)benzothiazole lysyl amidedihydrochloride salt; 5-Fluoro-2-(4′-amino-3′-methylphenyl)benzothiazolealanyl amide hydrochloride salt;5-Fluoro-2-(4′-amino-3′-methylphenyl)benzothiazole glycyl amidehydrochloride salt, 5-lodo-2-(4′-amino-3′-methylphenyl)benzothiazole;7-lodo-2-(4′-amino-3′-methylphenyl)benzothiazole;5-Fluoro-2-(4′-acetamido-3′-methylphenyl)benzothiazole;5-Fluoro-2-(4′-amino-3′-cyanophenyl)benzothiazole;4-Fluoro-2-(4′-amino-3′-cyanophenyl)benzothiazole;6-Fluoro-2-(4′-amino-3′-cyanophenyl)benzothiazole;5-Fluoro-2-(4′-amino-3′-(hydroxymethyl)phenyl)benzothiazole;5,6-Difluoro-2-(4′-amino-3′methylphenyl)benzothiazole alanyl amidehydrochloride salt;5,6-Difluoro-2-(4′-amino-3′methylphenyl)benzothiazole lysyl amidedihydrochlororide salt; and5-Trimethylstannyl-2-(4′-amino-3′-methylphenyl)benzothiazole.
 12. Anarylbenzazole compound of claim 1 for use in therapy as an activetherapeutic substance wherein said arylbenzazole compound is an acidaddition salt derived from an acid selected from the group consistingof: hydrochloric, hydrobromic, sulphuric, nitric, phosphoric, maleic,salicylic, p-toluenesulphonic, tartaric, citric, lactobionic, formic,malonic, pantothenic, succinic, naphthalene-2-sulphonic,benzenesulphonic, methanesulphonic and ethanesulphonic.
 13. Aisoropically labelled arylbenzazole compound selected from the groupconsisting of 5-¹⁸Fluoro-2-(4′-amino-3′-methylphenyl)benzothiazole and6-¹⁸Fluoro-2-(4′-amino-3′-methylphenyl)benzothiazole.
 14. Apharmaceutical formulation comprising a compound of claim 1 and apharmaceuically acceptable carrier.
 15. A medical preparationcomprising: a therapeutically effective amount of a compound of claim 1and a pharmaceutically inert excipient.
 16. A unit dosage of apharmaceutical preparation as an antitumour agent in treating mammalscomprising a therapeutically-effective non-toxic amount of a compound ofclaim
 1. 17. A method of reducing or inhibiting cancer cell growth in amammal comprising administering to said mammal an effective amount of anpharmaceutical formulation according to claim
 14. 18. An arylbenzazolecompound of claim 1 or 2 wherein p=0, R⁵ and R⁶ represent a hydrogenatom, R³ represents a hydrogen atom, X represents a sulfur atom, and R²is selected from 3′-Me, 3′-Et, 3′-Br, 3′-Cl, 3′-CN or 3′-F.
 19. Anarylbenzazole compound of claim 1 or 2 wherein p=0, R⁵ and R⁶ representa hydrogen atom, R³ represents a hydrogen atom, X represents an oxygenatom, and R² represents 3′-1.
 20. An arylbenzazole compound of claim 1or 2 wherein p=0, R⁵ and R⁶ represent a hydrogen atom, R³ represents5′-Cl or 5′-Me, X represents an sulfur atom, and R² represents 3′-Cl.21. An arylbenzazole compound of claim 1 or 2 wherein p=0, R⁵ and R⁶represent a hydrogen atom, R³ represents 5′- Br, X represents an sulfuratom, and R² represents 3′-Cl.
 22. An arylbenzazole compound of claim 1or 2 wherein p=0, X represents a sulfur atom, wherein R³, R⁵ and R⁶ eachrepresent a hydrogen atom, Q represents a direct bond, n represents 1,R¹ represents 4-F, and R² is selected fom 3-CH₃, a hydrogen atom, 3-I,3-Cl, or 3-Br.
 23. An arylbenzazole compound of claim 1 or 2 whereinp=0, X represents a sulfur atom, wherein R³, R⁵ and R⁶ each represent ahydrogen atom, Q represents a direct bond, n represents 1, R¹ represents6-F, an R² is selected from 3-CH₃, a hydrogen atom, 3-I, 3-Cl, or 3-Br.24. An arylbenzazole compound of claim 1 or 2 wherein p=0, X represent asulfur atom, wherein R³, R⁵ and R⁶ each represent a hydrogen atom, Qrepresents a direct bond, n represents 1, R¹ represents 5-F, and R² isselected from 3-CH₃, a hydogen atom, 3-I, 3-Cl, or 3-Br.
 25. Anarylbenzazole compound of claim 1 or 2 wherein p=0, X represents asulfur atom, wherein R³, R⁵ and R⁶ each represent a hydrogen atom, Qrepresents a direct bond, n represents 1, R¹ represents 7-F, and R²represents 3-CH₃.
 26. An arylbenazole compound of claim 1 or 2 whereinp=0, X represents a sulfur atom, wherein R³, R⁵ and R⁶ each represent ahydrogen atom, Q represents a direct bond, n represents 2, R² represents3-CH₃, and R¹ represents a 4,5-diF, 4,6-diF, 5-7-diF, or 6,7-diF.
 27. Anarylbenzazole compound of claim 1 or 2 wherein p=0, X represents S, Qrepresents a direct bond, one of R⁵ and R⁶ represents a hydrogen atomand the other represents —C(O)CH(R⁸)NH₂, R³ represents a hydrogen atom,n represents 0, R² represents a hydrogen atom and R⁸ represents a groupselected from —CH₃ or (—CH₂)₄NH₂.
 28. An arylbenzazole compound of claim1 or 2 wherein p=0, X represents S, Q represents a direct bond, one ofR⁵ and R⁶ represents a hydrogen atom and the other represents—C(O)CH(R⁸)NH₂, R³ represents a hydrogen atom, n represents 0, R²represents 3-CH₃ and R⁸ represents a group selected from —CH₃,—(CH₂)₄NH₂, or CH₂OH.
 29. An arylbenzazole compound of claim 1 or 2wherein p=0, X represents S, Q represents a direct bond, one of R⁵ andR⁶ represents a hydrogen atom and the other represents —C(O)CH(R⁸)NH₂,R³ represents a hydrogen atom, n represents 0, R² represents 3-Cl and R⁸represents a group selected from —CH₃ or —(CH₂)₄NH₂.
 30. Anarylbenzazole compound of claim 1 or 2 wherein p=0, X represents S, Qrepresents a direct bond, one of R⁵ and R⁶ represents a hydrogen atomand the other represents —C(O)CH(R⁸)NH₂, R³ represents a hydrogen atom,n represents 1, R² represents 3-CH₃, R¹ represents 5-F, and R⁸represents a group selected from —CH₃, —(CH₂)₄NH₂, o, a hydrogen atom.31. An arylbenzazole compound of claim 1 or 2 wherein p=0, X representsS, Q represents a direct bond, one of R⁵ and R⁶ represents a hydrogenatom and the other represents —C(O)CH(R⁸)NH₂, R³ represents a hydrogenatom, n represents 1, R² represents 3-CH₃, R¹ represents 6F, and R⁸represents a group selected from —CH₃, —(CH₂)₄NH₂, or a hydrogen atom.32. An arylbenzazole compound represented by the structural formula IIbelow, or a phamaceutically acceptable salt thereof

wherein X represents S or O; R¹ independently represents fluoro, iodo ortrimethylrin; R² represents hydrogen, NO₂, N₃, halogen, alkyl, a halosubstituted or hydroxy substituted alkyl, CN or CF₃; R³ representshydrogen, halogen, alkyl, or a halo substituted or hydroxy substitutedalkyl; R⁴ independently represents alkyl, a halo substituted or hydroxysubstituted alkyl, hydroxyl, alkoxy or aralkoxy; R⁵ represents hydrogen,an amino acid, an alkyl, or a group

wherein Y represents O or S, and R⁷ represents alkyl or —CH(R⁸)NH₂ whereR⁸ represents hydrogen, or an optionally substituted alkyl; Q representsa direct bond, —CH₂— or —CH═CH—; p represents zero, 1 or 2; and nrepresents zero, 1, 2 or 3; subject to the following provisos: (a) alkylor substituted alkyl groups include linear, branched or cyclicstructures but when present as linear or branched structures in thecompound or as a moiety in another group such as alkoxy they arecomposed of less then ten carbon atoms; (b) p represents zero or 1 whenn represents 3; (c) when a group is optionally substituted, unlessotherwise specified, the substituent is selected from one or more of thefollowing: a halogen, OH, SH, NH₂, COOH and CONH₂.
 33. A method ofpreparing the compound of claim 32 comprising reacting a compound offormula III below

with a BOC-protected amino acid, followed by hydrochloric acid.